Semiconductor device and method of fabricating the same

Abstract

A semiconductor device including a substrate, a first transistor and a second transistor is provided. The first transistor includes a first gate structure over the first semiconductor fin. The first gate structure includes a first high-k layer and a first work function layer sequentially disposed on the substrate, a material of the first work function layer may include metal carbide and aluminum, and a content of aluminum in the first work function layer is less than 10% atm. The second transistor includes a second gate structure. The second gate structure includes a second high-k layer and a second work function layer sequentially disposed on the substrate. A work function of the first work function layer is greater than a work function of the second work function layer.

What is claimed is: 
     
         1 . A semiconductor device comprising:
 a first P-type transistor comprising a first high-k layer, a first bottom work function layer and a first upper work function layer, the first bottom work function being in contact with the first high-k layer and interposed between the first high-k layer and the first upper work function layer, wherein a material of the first bottom work function layer comprises metal carbide and aluminum, and a content of aluminum in the first bottom work function layer is less than 10% atm; and   a second P-type transistor located at a side of the first P-type transistor comprising a second high-k layer, a second bottom work function layer and a second upper work function layer, the second bottom work function layer being in contact with the second high-k layer and interposed between the second high-k layer and the second upper work function layer, wherein a material of the second bottom work function layer is the same as a material of the first bottom work function layer, the material of the second upper work function layer is different from a material of the first upper work function layer and a material of the second upper work function layer comprises aluminum of a content more than 10% atm.   
     
     
         2 . The semiconductor device of  claim 1 , wherein the metal carbide comprises titanium carbide. 
     
     
         3 . The semiconductor device of  claim 1 , wherein the material of the first bottom work function layer further comprises at least one selected from O and Cl. 
     
     
         4 . The semiconductor device of  claim 1 , wherein the material of the first upper work function layer is the same as the second bottom work function layer. 
     
     
         5 . The semiconductor device of  claim 1 , wherein a material of the second upper work function layer comprises TiAl, TiAlC, TaC, TaAlC, NbC, and VC. 
     
     
         6 . The semiconductor device of  claim 1 , wherein the first P-type transistor further comprises a first gate fill material disposed on the first upper work function layer, and the second P-type transistor further comprises a second gate fill material disposed on the second upper work function layer. 
     
     
         7 . The semiconductor device of  claim 6 , wherein the first P-type transistor further comprises a first glue layer disposed between the first upper work function layer and the first gate fill material, and the second P-type transistor further comprises a second glue layer disposed between the second upper work function layer and the second gate fill material. 
     
     
         8 . The semiconductor device of  claim 1 , further comprising:
 an N-type transistor disposed located at a side of the second P-type transistor, wherein the N-type transistor comprises a third high-k layer and a third work function layer disposed on the third high-k layer.   
     
     
         9 . The semiconductor device of  claim 8 , wherein a material of the third work function layer is the same as the material of the second upper work function layer. 
     
     
         10 . The semiconductor device of  claim 8 , wherein the third work function layer is in contact with the third high-K layer. 
     
     
         11 . A semiconductor device comprising:
 a first transistor comprising a first high-k layer, and a first work function layer disposed on the first high-k layer, the first work function layer comprising a first upper work function layer and a first bottom work function layer interposed between the first upper work function layer and the first high-k layer;   a second transistor comprising a second high-k layer, and a second work function layer disposed on the second high-k layer, the second work function layer comprising a second upper work function layer and a second bottom work function layer interposed between the second upper work function layer and the second high-k layer, wherein a material of the second upper work function layer is the same as the first bottom work function layer; and   a third transistor comprising a third high-k layer, and a third work function layer in contact with the third high-k layer, wherein a material of the third work function layer is the same as the first upper work function layer.   
     
     
         12 . The semiconductor device of  claim 11 , wherein the material of the first bottom work function layer comprises aluminum of a content less than 10% atm. 
     
     
         13 . The semiconductor device of  claim 11 , wherein the material of the first upper work function layer comprises aluminum of a content greater than 10% atm. 
     
     
         14 . The semiconductor device of  claim 11 , wherein the material of the first bottom work function layer comprises TiC. 
     
     
         15 . The semiconductor device of  claim 11 , wherein the material of the second bottom work function layer comprises TiC. 
     
     
         16 . The semiconductor device of  claim 11 , wherein the material of the second bottom work function layer comprises aluminum of a content less than 10% atm. 
     
     
         17 . The semiconductor device of  claim 11 , wherein the first bottom work function layer is in contact with the high-k layer and the second bottom work function layer is in contact with the high-k layer. 
     
     
         18 . A method of fabricating a semiconductor device, comprising:
 forming a first P-type transistor comprising a first high-k layer, a first bottom work function layer and a first upper work function layer, the first bottom work function layer being in contact with the first high-k layer and interposed between the first high-k layer and the first upper work function layer, wherein a material of the first bottom work function layer comprises metal carbide and aluminum, a content of aluminum in the first bottom work function layer is less than 10% atm and a material of the first upper work function layer comprises aluminum of a content greater than 10% atm; and   forming a second P-type transistor located at a side of the first P-type transistor, the second P-type transistor comprising a second high-k layer, a second bottom work function layer and a second upper work function layer, the second bottom work function being in contact with the second high-k layer and interposed between the second high-k layer and the second upper work fundtion layer, wherein a material of the second bottom work function layer is the same as a material of the first bottom work function layer, the material of the second upper work function layer is different from a material of the first upper work function layer and a material of the second upper work function layer comprises aluminum of a content more than 10% atm,   wherein a formation of the first bottom work function layer comprises:   depositing the material of the first bottom work function layer on the first high-k layer by using a first precursor and a second precursor, wherein the first precursor comprises metal chloride, and the second precursor comprises tri-methyl-aluminum.   
     
     
         19 . The method of  claim 18 , wherein the metal chloride comprises TiCl4. 
     
     
         20 . The method of  claim 18 , wherein the depositing comprises an atomic layer deposition.